1. Field of the Invention
The present invention relates to a plasma processing apparatus that processes a substrate-like specimen such as a semiconductor wafer transferred and arranged in a decompressed processing chamber within a vacuum container by the use of plasma formed in the processing chamber, and includes a plurality of members detachably arranged at vertical positions and constituting the vacuum container.
2. Description of the Related Art
A generally-known semiconductor wafer manufacturing apparatus for manufacturing a semiconductor device from a substrate-like specimen such as a semiconductor wafer applies processing with plasma such as etching to a film layer to be processed of a film structure having a plurality of film layers including a mask pre-formed on the upper surface of the specimen arranged in a decompressed processing chamber within a vacuum container. In such a plasma processing apparatus, for example, a processing gas is introduced into the decompressed processing chamber inside the vacuum container, an electric field or a magnetic field is supplied to the processing chamber to excite the processing gas and produce plasma, and the film layer to be processed on the semiconductor wafer suctioned and held on a specimen stage by electrostatic force is processed by chemical reactions between active particles such as radicals included in the plasma and the material of the film layer to be processed, and interactions including physical reactions such as sputtering of charged particles such as ions.
The particles of reaction products formed in the processing chamber during the processing of a specimen such as a wafer float in the processing chamber and stick to the inner wall surfaces. As the total number of processed specimens and the total amount of processing time increase, the deposited particles accumulate and form a film on the inner surface of the processing chamber. As a result, the deposited matter interacts with plasma formed in the processing chamber, and its flakes and particles float again in the processing chamber and stick to the surface of the specimen to contaminate the specimen and the film structure for a semiconductor device circuit formed on the surface of the specimen. This causes a problem of deterioration in performance of the semiconductor device to be produced by the processing, thereby leading to occurrence of failure and yield reduction. In addition, the amount of interaction between the matter deposited to the inner surface of the processing chamber and the plasma influences the values of potential, density, and strength of the plasma above the upper surface of the specimen and the distribution of the plasma. With the increases in the total number of processed specimens and the total amount of processing time, the increase of the deposited matter affects the results of processing on specimens. Accordingly, the results of processing on a plurality of specimens fluctuate even from the beginning. This causes a problem that the processed shapes increasingly deviate from a desired one over time.
To solve these problems, conventionally, when it is determined that the total number of processed specimens and the total amount of processing time have reached predetermined values, the operation of the plasma processing apparatus is temporarily stopped, and the processing chamber is cleaned to eliminate deposited matter from the inner surface of the processing chamber and recover the inner surface of the processing chamber to an extent that desired processing results can be obtained. For the cleaning, the processing chamber inside the vacuum container is subjected to atmospheric (air) pressure and opened to the air, and the surfaces of members in the processing chamber are wiped (wet-cleaned) with cloth or the like using a drug solution.
To perform such cleaning, it is necessary to open the interior of the processing chamber under air pressure and halt the processing of a specimen at each cleaning time. Accordingly, it is important to shorten the time taken for the cleaning as much as possible to enhance the operating rate of the vacuum processing apparatus and improve the entire processing efficiency. In addition, the particles of reaction products and the like stick to not only the surfaces of the members in the processing chamber but also the surface of the specimen stage arranged in the processing chamber to hold a semiconductor wafer on the upper surface. Accordingly, it is also necessary to perform wet-cleaning or the like to eliminate the deposited matter from the surfaces of the specimen stage other than the upper surface on which the specimen is to be placed.
The time taken for wet-cleaning of the surfaces of the members constituting the processing chamber can be shorten by detaching the vacuum container or its parts exposed to the vacuum processing atmosphere and carrying reaction products and then replacing it with a new or cleaned one. One of such conventional techniques is known as disclosed in JP-2005-252201-A, for example. As the conventional technique, there is disclosed a vacuum processing apparatus that includes an upper inner cylindrical chamber and a specimen stage constituting a processing chamber for processing a subject to be processed within an external chamber, and a lower internal cylindrical chamber arranged at an exhaust part side.
According to this conventional technique, for maintenance of the apparatus, a discharge chamber base plate arranged on the top of the upper inner cylindrical chamber and constituting a discharge chamber for generating plasma is rotated and lifted upward around a hinge portion arranged at a transfer chamber side as a supporting point to produce a working space for the upper inner chamber, and the upper inner chamber is lifted off the outer chamber. In addition, according to this conventional technique, a specimen stage base plate to which a ring-shaped support base member (specimen stage block) including support beams arranged and fixed around the vertical center of the specimen stage as an axis is fixed, is rotated and lifted around the hinge portion arranged at the transfer chamber side as a supporting point to produce a working space for the lower inner chamber, and the lower inner chamber is lifted off the outer chamber, and the members of the chamber are replaced by other ones with surfaces regarded as being unused or cleaned.
By arranging the support beams axisymmetrically with respect to the vertical center of the specimen stage as an axis (that is, the shape of a gas flow path relative to the central axis of the specimen stage is in approximately concentric axis symmetry), a gas and other components (processing gas, and particles and reaction products in the plasma) in the space above the specimen stage within the upper inner cylindrical chamber are passed through the space between the support beams and are discharged via the lower inner cylindrical chamber. Accordingly, the gas flows uniformly in the circumferential direction of the subject to be processed, which allows uniform processing of the subject to be processed.
Meanwhile, JP-2005-516379-A discloses a cantilever substrate support part with an electrostatic chuck assembly that is attachable to or detachable from a vacuum processing chamber by forming (horizontally) openings in side walls of the chamber. Since the substrate support part including the specimen stage can be removed from the vacuum container, the interior of the processing chamber does not need to be opened to clean the surfaces of the specimen stage. In addition, the inner side walls of the processing chamber and the surfaces of the substrate support part including the specimen stage can be cleaned simultaneously to shorten the time taken for working, reduce the non-operating time of the apparatus, and improve the entire processing efficiency.